21258256 has 40 divisors (see below), whose sum is σ = 43729344. Its totient is φ = 9989760.

The previous prime is 21258253. The next prime is 21258301. The reversal of 21258256 is 65285212.

It is not an unprimeable number, because it can be changed into a prime (21258253) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21975 + ... + 22921.

Almost surely, 2^21258256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21258256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21864672).

21258256 is an abundant number, since it is smaller than the sum of its proper divisors (22471088).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21258256 is a wasteful number, since it uses less digits than its factorization.

21258256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1039 (or 1033 counting only the distinct ones).

The product of its digits is 9600, while the sum is 31.

The square root of 21258256 is about 4610.6676306149. The cubic root of 21258256 is about 277.0187791098.

The spelling of 21258256 in words is "twenty-one million, two hundred fifty-eight thousand, two hundred fifty-six".